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Biomedical subjects

J Fontaine

Publications and source records attributed to J Fontaine.

At least 145 records · Page 8Linked to original sources
PubMed1978

Sensitization by caerulein of guinea-pig ileum to contractions by acetylcholine, histamine, 5-hydroxytryptamine and nicotine.

Low concentrations (0.63 and 1.25 ng/ml) of caerulein increase the submaximal contractions of the guinea-pig isolated ileum induced by several agonists and electrical stimulation. These effects of the polypeptide are due partly to neuronal pathways (i.e., a ganglionic stimulation) and partly to a non specific muscular sensitization. At higher concentrations of caerulein the effects of all the agonists were decreased. This seems related to the contractile effect of the peptide itself on the longitudinal muscle which interfers non specifically with the development of contractions induced by any other agonist.

Acetylcholine↗
PubMed1978

Pharmacological analysis of the effects of substituted benzamides on the isolated guinea-pig ileum. Study of metoclopramide, sulpiride, bromopride, tiapride and sultopride.

The effects of metoclopramide (Mcp), sulpiride (Sp) and some of their derivatives: bromopride (Br), tiapride (Ti) and sultopride (Stp) have been compared on the guinea-pig isolated ileum. 1. Br and Ti have, like Mcp, and indirect cholinergic stimulating effect on the intestinal smooth muscle. Sp and Stp are devoid of such an effect. 2. At high doses, all the benzamides have a direct inhibitory effect on the ileum. 3. Mcp, Br and Ti (10(-5)M) potentiate the responses of the ileum to acetylcholine (ACh). At high doses (10(-4)M) the effects of all benzamides on the responses to ACh as well as to histamine (H) are mostly inhibitory. 4. Mcp and Br (10(-5)M) inhibit the responses of the ileum to serotonin (5HT) while Ti, Sp and Stp potentiate them. 5. Neural pathways and calcium mechanisms are involved in the potentiations of ACh and 5HT responses since the enhancements observed are abolished in the presence of tetrodotoxin or in the absence of Ca++.

Acetylcholine↗
PubMed1977

Smooth muscle sensitization induced by colchicine: is it an in vitro property of antitubulin agents?

Colchicine 0.1 microgram/ml induces a reversible increase of guinea-pig isolated ileum contractions (50 to 60% of maximal contractions) to acetylcholine, nicotine and PGE2. At 1 microgram/ml, it induces an irreversible increase of similar contractions to acetylcholine and 5-hydroxytryptamine. Low concentrations of indomethacin are able to reduce or even to abolish this increase. This smooth muscle sensitization could be related to the ability of colchicine to stimulate prostaglandin biosynthesis. Vinblastine has been described to induce a similar in vitro sensitization of guinea-pig isolated ileum. This effect might be also a non-specific property of antitubulin agents. The relationships between such an in vitro sensitization and the clinical effects of colchicine, including diarrhea, remain unclear.

Animals↗
PubMed1977

Effect of high concentrations of non-steroidal and steroidal antiinflammatory drugs on prostaglandin-induced contractions of the guinea-pig isolated ileum.

In addition to their well-known effect at low concentrations on prostaglandin synthesis or their release and production, 11 non-steroidal antiinflammatory drugs and 4 antiinflammatory steroids exhibit at high concentrations a direct antagonism on certain prostaglandin actions. This is demonstrated on PGE1- and PGF2alpha-induced contractions of guinea-pig isolated ileum when compared to acetylcholine-induced contractions. This inhibitory effect is totally reversible after washing out the drugs from the organ bath.

Animals↗
PubMed1977

A possible role of prostaglandins in guinea-pig isolated ileum contractions to serotonin.

Nine non-steroidal antiinflammatory drugs have been tested for their effect on contractions to serotonin of the guinea-pig isolated ileum. They exert a potent inhibition which is totally reversible by washing out the drugs. It is also well reversed by the addition of small amounts of PGE1 to the bath. It is concluded that prostaglandins exert a role in these contractions to serotonin which is probably specific as well as non specific.

Animals↗
PubMed1977

The effects of non-steroidal anti-inflammatory drugs on cholinergic and histamine-induced contractions of guinea-pig isolated ileum.

1 Eleven non-steroidal anti-inflammatory drugs (NSAID) reversibly inhibited contractions of the longitudinal muscle of the guinea pig isolated ileum induced by acetylcholine, histamine, electrical transmural stimulation and nicotine in this order of increasing potency. 2. After the addition of prostaglandins E1, E2 or F2alpha, with partially effective concentrations of NSAID (but not with higher concentrations which almost totally prevented the responses) the inhibitory effects of NSAID were reversibly lost, except for electrically induced contractions and prostaglandin F2alpha. 3 The effects of NSAID may be due to actions on biological membranes or on distribution of ions in addition to their inhibitory effect on prostaglandin synthesis. Prostaglandins may reverse the inhibition by non-selective sensitization of smooth muscle to various agonists.

Acetylcholine↗